I tried to end an old contract but the Upwork instructions don't seem to be updated/accurate. They say there should be an "end contract" option when you go to the options menu for a specific contract under "All Contracts." I don't see this.
That's when you click three dots on the All Contracts page. But you need to go to the specific contract and click three dots there. You'll have three options then: Propose new contract, Give a refund, End contract.